Field of the Invention
The present invention relates to a substrate processing technology for performing a processing over a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a glass substrate for a photomask, a substrate for a solar cell or the like (which will simply be hereinafter referred to as a “substrate”).
Description of the Background Art
As a substrate processing device for performing such a processing, Japanese Patent Application Laid-Open Nos. 2014-67778 and 2014-67780 disclose a device for supplying a processing solution to a substrate and processing the substrate while rotating a holding member for holding the substrate horizontally from below and a shielding plate opposed to an upper surface of the substrate. The shielding plate is slightly larger than the substrate and is disposed to cover the substrate in an upper close position of the substrate. A tip part of a first engaging portion protruded downward from a peripheral edge part of the shielding plate and a tip part of a second engaging portion protruded upward from a peripheral edge part of the holding member are engaged with each other in a position between the substrate and the holding member. A rotational drive rotates the holding member with the holding member and the shielding plate thus engaged with each other. Consequently, the shielding plate is rotated and driven at an equal rotating speed in the same rotating direction as the holding member so that refuse or mist is prevented from sticking to the upper surface of the substrate.
Moreover, Japanese Patent Application Laid-Open No. 2010-56218 discloses a device including a holding member for holding a substrate horizontally from below and a shielding plate opposed to an upper surface of the substrate and supplying a processing solution to a to-be-processed surface of the substrate to process the substrate while rotating the holding member and the shielding plate respectively. The shielding plate is provided in order to shield an atmosphere of a surface of the substrate from an external atmosphere thereof. The shielding plate is slightly larger than the substrate and is disposed to cover the substrate above the substrate. The shielding plate has an opposed surface which is opposed to the upper surface of the substrate and a peripheral wall portion. The peripheral wall portion is protruded downward from a peripheral edge part of the shielding plate and surrounds a whole circumference of the peripheral edge part of the substrate. A tip edge of the peripheral wall portion is positioned closer to the holding member than the substrate held by the holding member. An inner peripheral surface of the peripheral wall portion takes a shape such as a side surface of a truncated cone which has an opposed surface to be an upper surface and a diameter thereof is gradually increased to approach the tip edge side from the opposed surface side. The processing solution emitted to the substrate is discharged from the surface of the substrate by the rotation of the substrate and is discharged from a clearance between a peripheral edge part of an upper surface of the holding member and a tip edge of the shielding plate.
Furthermore, Japanese Patent Application Laid-Open No. 2011-211094 discloses a device including a holding member for horizontally holding a substrate from below and a disk-shaped nozzle provided between the holding member and the substrate. The disk-shaped nozzle is opposed to a central part of a lower surface of a substrate W. The device discharges a processing solution from the disk-shaped nozzle toward a central part of the lower surface of the substrate while rotating the holding member. The discharged processing solution is moved from the central part of the lower surface to a peripheral edge part and is thus discharged from the peripheral edge part to an outside of the substrate in order to cover the whole lower surface of the substrate by centrifugal force. Consequently, the whole lower surface of the substrate is processed.
In addition, Japanese Patent Application Laid-Open No. 11-102882 (1999) discloses a device including a spin base (a “holding member”) to be rotated while holding a substrate substantially horizontally by a chuck pin, a cover member opposed in parallel with a predetermined interval formed from an upper surface of the substrate, and a nozzle for selectively supplying hydrofluoric acid, pure water or the like to the upper surface of the substrate via a through hole provided on a central part of the cover member. Moreover, the device further includes a cylindrical processing cup having a bottom face. The spin base is rotatably supported above the bottom face of the processing cup. The device further includes a cylindrical guard. The guard is provided along an inner peripheral surface of a side wall of the processing cup and surrounds the spin base. The guard is moved upward and downward between predetermined lower and upper positions by a driving mechanism. A solution supplied from the nozzle to the substrate in the processing of the substrate sticks to a side surface of the spin base in discharge from the substrate. Therefore, the device further includes a cleaning nozzle for cleaning the side surface of the spin base. The cleaning nozzle is provided on the bottom face of the processing cup apart from the spin base outward in a radial direction. The cleaning nozzle discharges a cleaning liquid obliquely upward toward the side surface of the spin base and cleans the side surface of the spin base.
Referring to the devices disclosed in the Japanese Patent Application Laid-Open Nos. 2014-67778 and 2014-67780, however, a connecting part of the first and second engaging portions for engaging the shielding plate with the holding member is provided above the holding member. For this reason, there is a problem in that the processing solution supplied to the to-be-processed surface of the substrate and discharged from the peripheral edge part of the substrate to the outside by centrifugal force is splashed back toward the substrate side by a joint of the connecting part or the like and thus sticks to a surface (“a non-processed surface”) other than the to-be-processed surface of the substrate, resulting in generation of a defect such as a particle.
Referring to the device disclosed in the Japanese Patent Application Laid-Open No. 2010-56218, furthermore, there is a small annular space between the inner peripheral surface of the peripheral wall portion and the peripheral edge part of the substrate in the space surrounded by the shielding plate and the holding member. For this reason, there is a problem in that the processing solution discharged from the substrate and splashed back by the inner peripheral surface of the peripheral wall portion reaches the non-processed surface of the substrate and sticks thereto, resulting in generation of a defect on the substrate.
Referring to the device disclosed in the Japanese Patent Application Laid-Open No. 2011-211094, moreover, there is a problem in that a part of the processing solution discharged to the lower surface of the substrate drops and sticks onto the upper surface of the holding member from the lower surface of the substrate and remains as it is.
In addition, the upper end part of the guard is usually extended obliquely upward toward a rotating shaft of the spin base. The substrate processing device disclosed in the Japanese Patent Application Laid-Open No. 11-102882 (1999) supplies the solution from the nozzle to the substrate with the guard disposed in an upper position. The supplied solution scatters in the discharge from the substrate and also sticks to the inner peripheral surface of the guard. When the processing is repeated in a state in which the sticking solution remains, a deposit obtained by drying and solidifying the solution is gradually accumulated on the guard. When such a deposit is peeled, a particle is caused. Since the upper end part of the guard is close to the substrate, the deposit sticking to the upper end part tends to cause the particle.
Referring to the device disclosed in the Japanese Patent Application Laid-Open No. 11-102882 (1999), however, there is a problem in that the inner peripheral surface of the guard cannot be cleaned by the cleaning nozzle for cleaning the side surface of the spin base. Furthermore, there is a problem in that a structure of the device is complicated and a manufacturing cost is thus increased if a dedicated cleaning nozzle for discharging the cleaning liquid toward the inner peripheral surface of the guard is further provided, for example. In order to effectively suppress the particle, moreover, it is effective to clean the solution sticking to the inner peripheral surface of the upper end part of the guard. However, there is a problem in that the cleaning liquid scatters from the upper end part of the guard toward the substrate side and thus sticks to the substrate when the cleaning nozzle discharges the cleaning liquid from below toward the inner peripheral surface of the upper end part in the state in which the spin base holds the substrate. In addition, there is also a problem in that the guard needs to be cleaned after the substrate is retreated from the spin base if the sticking of the cleaning liquid is to be avoided.